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Several building energy simulation programs have been developed to evaluate the indoor conditions and energy performance of buildings. As a fundamental component of heating, ventilating, and air conditioning loads, each building energy modeling tool calculates the heat and moisture exchange among the outdoor environment, building envelope, and indoor environments. This paper presents a simplified heat and moisture transfer model of the building envelope, and case studies for building performance obtained by different heat and moisture transfer models are conducted to investigate the contribution of the proposed steady-state moisture flux (SSMF) method. For the analysis, three representative humid locations in the United States are considered: Miami, Atlanta, and Chicago. The results show that the SSMF model effectively complements the latent heat transfer calculation in conduction transfer function (CTF) and effective moisture penetration depth (EMPD) models during the cooling season. In addition, it is found that the ceiling part of a building largely constitutes the latent heat generated by the SSMF model.
Joowook Kim; Michael Brandemuehl. Application Method of a Simplified Heat and Moisture Transfer Model of Building Construction in Residential Buildings. Energies 2021, 14, 4180 .
AMA StyleJoowook Kim, Michael Brandemuehl. Application Method of a Simplified Heat and Moisture Transfer Model of Building Construction in Residential Buildings. Energies. 2021; 14 (14):4180.
Chicago/Turabian StyleJoowook Kim; Michael Brandemuehl. 2021. "Application Method of a Simplified Heat and Moisture Transfer Model of Building Construction in Residential Buildings." Energies 14, no. 14: 4180.
District heating (DH) is an energy efficient building heating system that entails low primary energy consumption and reduced environmental impact. The estimation of the required heating load provides information for operators to control district heating systems (DHSs) efficiently. It also yields historical datasets for intelligent management applications. Based on the existing virtual sensor capabilities to estimate physical variables, performance, etc., and to detect the anomaly detection in building energy systems, this paper proposes a virtual sensor-based method for the estimation of DH energy consumption in a residential building. Practical issues, including sensor absences and limited datasets corresponding to actual buildings, were also analyzed to improve the applicability of virtual sensors in a building. According to certain virtual sensor development processes, model-driven, data-driven, and grey-box virtual sensors were developed and compared in a case study. The grey-box virtual sensor surpassed the capabilities of the other virtual sensors, particularly for operation patterns corresponding to low heating, which were different from those in the training dataset; notably, a 16% improvement was observed in the accuracy exhibited by the grey-box virtual sensor, as compared to that of the data-driven virtual sensor. The former sensor accounted for a significantly wider DHS operation range by overcoming training data dependency when estimating the actual DH energy consumption. Finally, the proposed virtual sensors can be applied for continuous commissioning, monitoring, and fault detection in the building, since they are developed based on the DH variables at the demand side.
Sungmin Yoon; Youngwoong Choi; Jabeom Koo; Yejin Hong; Ryunhee Kim; Joowook Kim. Virtual Sensors for Estimating District Heating Energy Consumption under Sensor Absences in a Residential Building. Energies 2020, 13, 6013 .
AMA StyleSungmin Yoon, Youngwoong Choi, Jabeom Koo, Yejin Hong, Ryunhee Kim, Joowook Kim. Virtual Sensors for Estimating District Heating Energy Consumption under Sensor Absences in a Residential Building. Energies. 2020; 13 (22):6013.
Chicago/Turabian StyleSungmin Yoon; Youngwoong Choi; Jabeom Koo; Yejin Hong; Ryunhee Kim; Joowook Kim. 2020. "Virtual Sensors for Estimating District Heating Energy Consumption under Sensor Absences in a Residential Building." Energies 13, no. 22: 6013.
The Passive House standard has become the standard for many countries in the construction of the Zero Energy Building (ZEB). Korea also adopted the standard and has achieved great success in building energy savings. However, some issues remain with ZEBs in Korea. Among them, this study aims to discuss overheating issues. Field measurements were carried out to analyze the overheating risk for a library built as a ZEB. A data-driven overheating risk prediction model was developed to analyze the overheating risk, requiring only a small amount of data and extending the analysis throughout the year. The main factors causing overheating during both the cooling season and the intermediate seasons are also analyzed in detail. The overheating frequency exceeded 60% of days in July and August, the midsummer season in Korea. Overheating also occurred during the intermediate seasons when air conditioners were off, such as in May and October in Korea. Overheating during the cooling season was caused mainly by unexpected increases in occupancy rate, while overheating in the mid-term was mainly due to an increase in solar irradiation. This is because domestic ZEB standards define the reinforcement of insulation and airtight performance, but there are no standards for solar insolation through windows or for internal heat generation. The results of this study suggest that a fixed performance standard for ZEBs that does not reflect the climate or cultural characteristics of the region in which a ZEB is built may not result in energy savings at the operational stage and may not guarantee the thermal comfort of occupants.
Yue Yuan; Jisoo Shim; SeungKeon Lee; Doosam Song; Joowook Kim. Prediction for Overheating Risk Based on Deep Learning in a Zero Energy Building. Sustainability 2020, 12, 8974 .
AMA StyleYue Yuan, Jisoo Shim, SeungKeon Lee, Doosam Song, Joowook Kim. Prediction for Overheating Risk Based on Deep Learning in a Zero Energy Building. Sustainability. 2020; 12 (21):8974.
Chicago/Turabian StyleYue Yuan; Jisoo Shim; SeungKeon Lee; Doosam Song; Joowook Kim. 2020. "Prediction for Overheating Risk Based on Deep Learning in a Zero Energy Building." Sustainability 12, no. 21: 8974.
This study uses long-term field measurements to quantify the indoor humidity generation rates of low-income households vulnerable to condensation and related problems. We found that the mean internal moisture excess of low-income households in Korea was 4.69 g/m3 higher than those of prior studies. Indoor water vapor generation rates of various activities considering the life style of low-income households were also quantified. The moisture generation rates of the shower and bath were 125.3 g/event and 51.1 g/event, respectively, and showed a similar or lower value compared to the existing results. The moisture generation rate of cooking showed the largest difference due to the residential characteristics of low-income households, such as cooking less frequently due to meal delivery services from the welfare center and the lower number of residents per household. Even though the moisture generation rates of low-income households for certain activities showed lower values compared to the results of prior studies, the indoor conditions were very humid due to the lower ventilation rates and studio-type open floor plan.
Younhee Choi; Younghoon Lim; Joowook Kim; Doosam Song. Why Does a High Humidity Level Form in Low-Income Households despite Low Water Vapor Generation? Sustainability 2020, 12, 7563 .
AMA StyleYounhee Choi, Younghoon Lim, Joowook Kim, Doosam Song. Why Does a High Humidity Level Form in Low-Income Households despite Low Water Vapor Generation? Sustainability. 2020; 12 (18):7563.
Chicago/Turabian StyleYounhee Choi; Younghoon Lim; Joowook Kim; Doosam Song. 2020. "Why Does a High Humidity Level Form in Low-Income Households despite Low Water Vapor Generation?" Sustainability 12, no. 18: 7563.
Building energy savings and occupant thermal comfort are the main issues in building technology. As such, the development of energy-efficient heating, ventilation, and air-conditioning (HVAC) systems and the control strategies of HVAC systems are emerging as important topics in the HVAC industry. Variable refrigerant flow (VRF) systems have efficient energy performance, so the use of VRF systems in buildings is increasing. However, most studies on VRF systems focus on improving mechanical efficiency, with few studies on energy-efficient control while satisfying the thermal comfort of occupants. The goal is to estimate the energy-saving potential of adjusting the temperature set-points and dead-band (range) in VRF air-conditioned building. To do so, we analyzed the influence of control strategies of a VRF system on human thermal comfort and energy consumption using a simulation method. The results showed that energy consumption can be reduced by 25.4% for predicted mean vote (PMV)-based control and 27.0% for the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) comfort range control compared with the typical set-point temperature control of a VRF system. The indoor thermal environments of the analyzed control strategies are controlled in the thermal comfort range, which is based on a PMV at ±0.5. Compared with the typical set-point control, PMV and ASHRAE comfort range-based control reduced the operation time of the compressor in the VRF system.
Joowook Kim; Doosam Song; Suyeon Kim; Sohyun Park; Youngjin Choi; Hyunwoo Lim. Energy-Saving Potential of Extending Temperature Set-Points in a VRF Air-Conditioned Building. Energies 2020, 13, 2160 .
AMA StyleJoowook Kim, Doosam Song, Suyeon Kim, Sohyun Park, Youngjin Choi, Hyunwoo Lim. Energy-Saving Potential of Extending Temperature Set-Points in a VRF Air-Conditioned Building. Energies. 2020; 13 (9):2160.
Chicago/Turabian StyleJoowook Kim; Doosam Song; Suyeon Kim; Sohyun Park; Youngjin Choi; Hyunwoo Lim. 2020. "Energy-Saving Potential of Extending Temperature Set-Points in a VRF Air-Conditioned Building." Energies 13, no. 9: 2160.
Energy efficiency policies are made to reduce the energy necessary to achieve a given level of indoor heating and to decrease the greenhouse gas emission worldwide. National and state regulators routinely tighten the energy efficiency building code appliance standards. In particular, for low-income households, the government has been implementing an energy efficiency program, and the most common measures include furnace replacement, attic and wall insulation, and infiltration reduction. The belief that the energy efficiency programs are beneficial and lead to energy reductions often fails, which is known as the ‘efficiency gap.’ This paper analyzed the effect of input data in calculating the energy savings of the energy efficiency program for low-income households as a cause of the energy efficiency gap in energy efficiency treatments for low-income households. According to the retrofit of the low-income household, the energy saving effect predicted through the input data of detailed measurement was 65%, which was higher than 41% of the conventional prediction method (walk-through audit). The resulting greenhouse gas (GHG) reduction effect was also the same as the energy savings, and the results predicted by the existing prediction methods were less predicted than the detailed measurement results.
Joowook Kim; Jemin Myoung; Hyunwoo Lim; Doosam Song. Efficiency Gap Caused by the Input Data in Evaluating Energy Efficiency of Low-Income Households’ Energy Retrofit Program. Sustainability 2020, 12, 2774 .
AMA StyleJoowook Kim, Jemin Myoung, Hyunwoo Lim, Doosam Song. Efficiency Gap Caused by the Input Data in Evaluating Energy Efficiency of Low-Income Households’ Energy Retrofit Program. Sustainability. 2020; 12 (7):2774.
Chicago/Turabian StyleJoowook Kim; Jemin Myoung; Hyunwoo Lim; Doosam Song. 2020. "Efficiency Gap Caused by the Input Data in Evaluating Energy Efficiency of Low-Income Households’ Energy Retrofit Program." Sustainability 12, no. 7: 2774.
Building airflow is a main factor in indoor air and environmental qualities. In particular, stack-induced airflow can cause indoor environmental problems in high-rise buildings over the winter due to the strong driving force (pressure difference). The goal of this study was to identify the actual characteristics of stack-driven environmental problems in real high-rise residential buildings through a field survey and airflow simulation. We collected the actual resident complaints (140 cases) raised in six high-rise residential buildings in South Korea during three years. The most frequent complaints were airflow noise and drafts at residential entrance doors. Then, by a calibrated airflow simulation, we identified the unknown pressure differences that caused these two problems. Based on the pressure differences, this study could determine problem occurrence rates for noise and drafts depending on given pressure differences. Apart from the existing allowable or reference pressure difference (50 Pa) across doors suggested by ASHRAE and European standards (EN 12101-6), which is related to emergency escape, three reference levels were suggested: (1) tight: 25 Pa, (2) normal: 40 Pa, and (3) loose: 65 Pa. These values were intended to be used as the reference in predicting or solving the stack-driven problems. Finally, we successfully predicted the frequency of these problem occurrences over the winter in a target building, using a coupled airflow and thermal simulation. These results showed the importance of the newly suggested references, 25 Pa or 40 Pa rather than 50 Pa, in identifying the stack-driven airflow noise and draft.
Sungmin Yoon; Doosam Song; Jaehun Kim; Joowook Kim; Hyunwoo Lim; Junemo Koo. Identifying stack-driven indoor environmental problems and associated pressure difference in high-rise residential buildings: Airflow noise and draft. Building and Environment 2019, 168, 106483 .
AMA StyleSungmin Yoon, Doosam Song, Jaehun Kim, Joowook Kim, Hyunwoo Lim, Junemo Koo. Identifying stack-driven indoor environmental problems and associated pressure difference in high-rise residential buildings: Airflow noise and draft. Building and Environment. 2019; 168 ():106483.
Chicago/Turabian StyleSungmin Yoon; Doosam Song; Jaehun Kim; Joowook Kim; Hyunwoo Lim; Junemo Koo. 2019. "Identifying stack-driven indoor environmental problems and associated pressure difference in high-rise residential buildings: Airflow noise and draft." Building and Environment 168, no. : 106483.
Vertical and horizontal airflow occurs in high-rise buildings caused by wind pressure and temperature differences (thermal buoyancy), and heat, water vapor, and contaminants are transported along the air movement in high-rise buildings. To characterize transportation of the heat, water vapor, and contaminants with the airflow in a high-rise building, long-term measurements were taken in a high-rise residential building in Seoul, Korea, during the winter season. The analyzed building has 31 floors above ground and 5 floors underground and the height is approximately 110 m. The temperature, water vapor, and CO2 levels were measured at the elevator hall of the 7th floor, 13th floor, and 29th floor of the analyzed building. The measurement results indicated that the concentrations of heat, humidity, and contaminants (CO2) on the upper floors were all high compared to the lower floors because the outdoor air flows into the lower floors, moves upward through vertical shafts, such as the elevator core and staircases, and flows into the upper floors. This is due to the movement of heat, water vapor, and contaminants along the vertical air movement in high-rise buildings. In addition, the concentrations of heat, humidity, and CO2 in the high-rise residential building were the highest at the neutral pressure level (NPL, 13th floor) of the analyzed building. This is attributed to the poor ventilation performance at the NPL in high-rise buildings. As a result, the people who live on upper floors could be exposed to higher temperatures, humidity, and contaminants compared to those living on the lower floors in high-rise residential buildings.
Doosam Song; Sungmin Yoon; Chanwoul Jeong; Joowook Kim; Hyunwoo Lim. Heat, vapor, and CO2 transportation caused by airflow in high-rise residential buildings. Building and Environment 2019, 160, 106176 .
AMA StyleDoosam Song, Sungmin Yoon, Chanwoul Jeong, Joowook Kim, Hyunwoo Lim. Heat, vapor, and CO2 transportation caused by airflow in high-rise residential buildings. Building and Environment. 2019; 160 ():106176.
Chicago/Turabian StyleDoosam Song; Sungmin Yoon; Chanwoul Jeong; Joowook Kim; Hyunwoo Lim. 2019. "Heat, vapor, and CO2 transportation caused by airflow in high-rise residential buildings." Building and Environment 160, no. : 106176.
Many fuel poverty support programs have been implemented in the world. Energy-efficient retrofitting in low-income households is a main aspect of support programs in the context of energy saving, reduction of greenhouse gas emissions, and improvement of the thermal comfort and health of residents. This study analyzed the effects of an energy efficiency program for fuel poverty in Korea on the thermal comfort of residents. A total of 330 households were investigated wherein energy retrofits had been conducted. Indoor temperatures in the main bedroom and in the living room were recorded twice. The results showed that the average indoor air temperature in the surveyed households was 15.1 ± 3.7 °C, indicating that 95.2% of main bedrooms and 80.0% of living rooms did not meet the recommendations of the World Health Organization regarding temperature. These results indicated that the surveyed households did not use energy for heating their rooms, and an energy-saving effect due to the retrofits was difficult to expect. Accordingly, retrofit building or energy policies addressing fuel poverty are shown to be ineffective in the context of energy saving and thermal comfort in Korea. This article highlights issues that need to be analyzed to evaluate how effective the welfare program is. The results of this study alert policymaker to the need to improve the welfare policy; the methods proposed in this article will help them in their decisions.
Sowoo Park; Joowook Kim; Doosam Song. The Effect of an Energy Refurbishment Scheme on Adequate Warmth in Low-income Dwellings. Sustainability 2019, 11, 2574 .
AMA StyleSowoo Park, Joowook Kim, Doosam Song. The Effect of an Energy Refurbishment Scheme on Adequate Warmth in Low-income Dwellings. Sustainability. 2019; 11 (9):2574.
Chicago/Turabian StyleSowoo Park; Joowook Kim; Doosam Song. 2019. "The Effect of an Energy Refurbishment Scheme on Adequate Warmth in Low-income Dwellings." Sustainability 11, no. 9: 2574.
The vertical airflow is generated in high-rise buildings due to the stack effect caused by temperature differences between the inside and the outside of the building. The stack effect causes various problems such as strong airflow from doors, unpleasant noises through gaps, problems opening and closing elevator doors and hall doors, and difficulty in controlling the indoor temperature and ventilation systems. It also causes differences in infiltration and the associated heating load and/or energy consumptions by floor in high-rise residential buildings. In this study, the differences caused by the stack effect was investigated by field measurements and airflow and energy simulations. To obtain reliable airflow and energy results, the coupled airflow and energy simulation method was also proposed along with a two-step method of calibrating leakage data. The simulated results show the three kinds of heating load elements from airflow interactions with the stack-driven vertical airflow: (1) Outdoor air infiltration load, (2) interzone air infiltration load, and (3) increased heat transfer across the walls between corridors and households on lower floors. Based on their different characteristics by floor, the difference ratios between the minimum and maximum heating loads on floors were 291% and 1197%, respectively in the upper and lower sides from the neutral level. The three infiltration loads are responsible for 10.27% of total heating load over winter. This study implies that it is important to consider the stack-induced vertical airflow with the proposed simulation method in calculating the heating energy in high-rise residential buildings, particularly in cold regions.
Sungmin Yoon; Doosam Song; Joowook Kim; Hyunwoo Lim. Stack-driven infiltration and heating load differences by floor in high-rise residential buildings. Building and Environment 2019, 157, 366 -379.
AMA StyleSungmin Yoon, Doosam Song, Joowook Kim, Hyunwoo Lim. Stack-driven infiltration and heating load differences by floor in high-rise residential buildings. Building and Environment. 2019; 157 ():366-379.
Chicago/Turabian StyleSungmin Yoon; Doosam Song; Joowook Kim; Hyunwoo Lim. 2019. "Stack-driven infiltration and heating load differences by floor in high-rise residential buildings." Building and Environment 157, no. : 366-379.
The number of passive houses and zero-energy buildings being developed is increasing, as measures to reduce the rapidly increasing building energy consumption. While government building policies focus on energy savings, investors and the building market emphasize the initial investment cost. These conflicting perspectives obstruct the development of passive houses in the building market. In this study, a series of building energy analyses, including the effect of energy saving measures and economic information considering long-term economic benefit and incentives policy, will be presented. Analyses were performed on the energy-saving measures needed to improve the performance of single-family houses in Korea to that of the passive house standard, as well as the energy saving effect and increased cost. The application of energy saving measures for passive house implementation resulted in an additional cost of 1.85%–4.20% compared to the conventional reference house. In addition, the proposed passive house alternative shows a short payback period and life cycle cost (LCC) result, compared to a conventional building’s life cycle period. The possibility of passive house implementation is high, and developing the passive house is affordable for the investor or end user in Korea.
Jisoo Shim; Doosam Song; Joowook Kim. The Economic Feasibility of Passive Houses in Korea. Sustainability 2018, 10, 3558 .
AMA StyleJisoo Shim, Doosam Song, Joowook Kim. The Economic Feasibility of Passive Houses in Korea. Sustainability. 2018; 10 (10):3558.
Chicago/Turabian StyleJisoo Shim; Doosam Song; Joowook Kim. 2018. "The Economic Feasibility of Passive Houses in Korea." Sustainability 10, no. 10: 3558.
Energy recovery ventilators (ERV) have become popular in Korea for their use in minimizing heat loss in ventilation and maintaining indoor air quality (IAQ). The performance of ERV systems is determined by laboratory tests under prescriptive indoor and outdoor conditions. Typically, a fixed heat recovery efficiency of the ventilation system is used in building energy simulations. In this study, in order to analyze the heat recovery efficiency of an ERV under actual operating conditions, long-term field measurements were performed in a residential building in the winter. The results showed that the enthalpy heat recovery efficiencies fluctuated between 25% and 70% depending on the outdoor conditions. The sensible heat recovery efficiencies were between 30% and 65% and were proportional to the temperature difference between indoors and outdoors. The heat exchange efficiency of ERV was not constant but varied according to changes of indoor and outdoor conditions under actual operating conditions. A simulation method was used to analyze the effect of the ERV's variable heat exchange efficiency on heating energy demand in the heating season. Two cases were analyzed. Case 2 analyzed the variable heat exchange effectiveness of the ERV based on the field measurements. Case 1 examined the fixed effectiveness proposed by the manufacturer. Simulation results showed that the heating energy demand in Case 2 was 69% higher than that in Case 1. This means that the heating energy demand may be underestimated if the heat exchange efficiency of the ventilation system is assumed to be constant in the simulation.
Youn-Hee Choi; Doosam Song; Donghyun Seo; Joowook Kim. Analysis of the variable heat exchange efficiency of heat recovery ventilators and the associated heating energy demand. Energy and Buildings 2018, 172, 152 -158.
AMA StyleYoun-Hee Choi, Doosam Song, Donghyun Seo, Joowook Kim. Analysis of the variable heat exchange efficiency of heat recovery ventilators and the associated heating energy demand. Energy and Buildings. 2018; 172 ():152-158.
Chicago/Turabian StyleYoun-Hee Choi; Doosam Song; Donghyun Seo; Joowook Kim. 2018. "Analysis of the variable heat exchange efficiency of heat recovery ventilators and the associated heating energy demand." Energy and Buildings 172, no. : 152-158.
Korea relies significantly on imported fossil fuels to meet its energy needs. Moreover, about 50% of Korean residential buildings are apartment complexes. In this paper, the use of distributed generation (DG) technologies to serve the energy requirements for a typical Korean apartment complex is explored to reduce Korea’s dependence on fossil fuel and CO2 emissions. In particular, a series of sensitivity analyses is conducted using detailed simulation tools to determine the cost-effectiveness of DG systems to meet electrical and thermal loads of an apartment building in Daegu, Korea. The DG systems considered in the analysis include Photovoltaic (PV), Wind turbine, Microturbine, and Fuel Cell. The apartment complex is connected to the utility grid that with electricity typically generated using fossil fuels. It is found that a combination of the grid and Fuel Cell is the most cost effective approach to meet the electrical and thermal loads of the complex residential building with a cost of energy reduction of 12% compared to the grid only option.
Joowook Kim; Hyunwoo Lim; Moncef Krarti. Hybrid Distributed Power Generation for Apartment Building Complexes in Korea. ASME 2012 6th International Conference on Energy Sustainability, Parts A and B 2012, 1179 -1185.
AMA StyleJoowook Kim, Hyunwoo Lim, Moncef Krarti. Hybrid Distributed Power Generation for Apartment Building Complexes in Korea. ASME 2012 6th International Conference on Energy Sustainability, Parts A and B. 2012; ():1179-1185.
Chicago/Turabian StyleJoowook Kim; Hyunwoo Lim; Moncef Krarti. 2012. "Hybrid Distributed Power Generation for Apartment Building Complexes in Korea." ASME 2012 6th International Conference on Energy Sustainability, Parts A and B , no. : 1179-1185.